This invention relates to household laundry processes for combined washing and bleaching of fabrics, and to simultaneous removal of stains and fugitive dyes.
British Pat. No. 1,372,035 (Speakman) published on Dec. 23, 1975 related to a household washing and bleaching process for cotton fabrics utilizing photoactivating compounds, principally sulfonated zinc phthalocyanine, in a built detergent composition in the presence of visible light and atmospheric oxygen. In a patent of addition, British Pat. No. 1,408,144 published Jan. 28, 1976, Speakman disclosed a surfactant/builder composition which was dissolved in water to form a solution to which was added, both separately and together, sodium perborate and sulfonated zinc phthalocyanine. Bleaching effects of the combination were said to be greater than would have been expected from the two components acting independently. It was postulated that the sulfonated zinc phthalocyanine enabled evolved oxygen from the sodium perborate, which would otherwise escape unused as molecular oxygen, to be converted into singlet oxygen which acted as the active chemical bleaching agent.
U.S. Pat. No. 4,033,718 granted to Holcombe et al on July 5, 1977 teaches the use of specific mixtures of sulfonated zinc phthalocyanine species, principally tri- and tetra-sulfonates, as preferred bleach photoactivators.
Belgian Pat. No. 840,348 invented by Wiers, granted on Oct. 4, 1976 discloses the use of zinc phthalocyanine tri- and tetra-sulfonates as bleach photoactivators in unbuilt liquid detergent compositions.
British Pat. No. 1,372,036 invented by Speakman and published on Oct. 30, 1974 describes a washing machine provided with a source of visible light which irradiates wash liquor containing phthalocyanine photoactivator and fabrics. An example comparable to that described in British Pat. No. 1,408,144 described above showed results consistent therewith.
In Canadian patent application No. 274,869 filed Mar. 28, 1977, Goodman eliminated the blue-green staining problem inherent in previous work by using much reduced concentrations of zinc phthalocyanine sulfonate in conjunction with a long pre-wash soaking time. As little as 0.003% photoactivator was needed in conjunction with 18-hour soaking, which could optionally take place under illumination or in the dark. Light was, however, believed essential during the drying step which takes place after washing.
In Philippine patent applications Nos. 20,644 and 20,643 filed Jan. 11, 1978 substantially corresponding to U.S. applications Ser. Nos. 2414 and 2275, respectively, filed Jan. 10, 1979, Sakkab disclosed the use of many porphine derivatives as alternatives to zinc phthalocyanine sulfonate; these derivatives were solubilized by anionic, nonionic or cationic moieties introduced into the porphine molecule. Not only stain removal but also removal of fugitive dyes and improvement in overall whiteness of the fabrics was obtained.
In Philippine patent application No. 20,642 also filed Jan. 11, 1978 substantially corresponding to U.S. application Ser. No. 2415 filed Jan. 10, 1979, Sakkab disclosed the use of porphine derivatives in conjunction with cationic substances; previously thereto, usage of porphine derivatives as detergent bleaches had been limited to use with anionic, nonionic, semi-polar, ampholytic or zwitterionic surfactants. As in all previous disclosures, visible light was believed essential to operability of the bleaching process. The three Sakkab citations are incorporated herein by reference.
In all references identified above, zinc phthalocyanine sulfonate and other porphine bleaches have been referred to as "photosensitizers" or "photoactivators", and the processes of use have invariably involved the presence of visible light (640-690 nm.) at one or more stages of soaking, washing or drying. It has now been unexpectedly found that porphine bleach, in combination with peroxy bleach, is effective when the entire washing and drying process takes place in darkness.
Furthermore, the effectiveness of the combination of peroxy bleach with porphine bleach is so great that levels of peroxy and/or porphine bleach hitherto believed ineffective can be advantageously used. This represents an economic advantage, and one that might be particularly appreciated by those who are concerned about ecology and waste disposal.